Graphic privacy system



March 9, 1948.

J. v. L. HOGAN Er Al.A

GRAPHIC PRIVACY SYSTEM Filed June 4, 194s 3 Sheets-Sheet l &

INVENTbRs Jeff/7p VLJL'o'yczn/ i d. Resv-Zei BYM @Wzl/.M

ATORNEY March 9, 1948. J. v. I HoGAN'i-rr AL GRAPHIC PRIVACY SYSTEMvFiled June 4, 1943 3 Sheets-Sheet 2 INVENTOR Jail/lv VLJo r M ORNEYMarch 9, 1948. y.1. v, L. HOGAN E Al.

GRAPHIC PRIVACY SYSTEM Filed June 4, 1943 3 Sheets-Sheet 5 Patented Mar.9,

UNITED STATES 2.437.255 Acanarino PRIVACY SYSTEM John V. L. Hogan,Forest Hills, and Hugh C. Ressler, Bayside, N. Y., assignors toFaximlle,

Inc., New York, N. Y.,

g Wale a corporation of Dela- Application June 4, 1943, Serial No.489,654

7 Claims. 1

VThe present invention concerns enciphering and deciphering of graphicmaterial for privacy by automatic machinery.

One object is to provide means for mechanically and automaticallyenciphering and deciphering graphic material for privacy purposes.

v Another object is to provide an enciphering and deciphering machine inwhich a very large number of ciphering key combinations are possible.

Still another object is to provide a machine in which the keycombinations may be readily changed.

A further object is to provide a machine capable of varying degrees ofprivacy from a moderate order to a very high order.

A still further object is to provide a. machine for enciphering graphicmaterial in a form particularly Well adapted to facsimile transmission.

These and other objects will be evident from the detailed description ofthe inventionY given in connection with the various figures of thedrawing.

The ciphering loperations to be accomplished by the devices of thepresent invention consist of four fundamental operations. The firstoperation is, in effect, dividing the clear subject copy into a numberof horizontal strips of predetermined width. The second operation is thetransposition of these strips in an order predetermined by thehorizontal key selected, which key must be known by both the sender andthe receiver of the ciphered subject copy. The third operation consistsof dividing the partially enciphered copy (produced by operations 1 and2) into strips of predetermined width but at right angles to the f'irstdividing operation. The fourth step is the transposition of theresulting strips according to a mutually known key for the verticalrandomiz- King of the copy, which' may differ from the key first used.The result of the four operations is a ciphered message which can bedelivered to its destination by mail, by courier, by facsimile orotherwise.

Where additional security is required, the sub'- ject copy ciphered asabove describedmay be same four operations two or more times. Where asecond ciphering isused, it is preferred that the effective dividing ofthe copy be done along lines which fall midway between the dividinglines used for the first ciphering. Where three successive cipheringsare used,the second and third divisions "may each be displaced byone-third of the strip-width, etc.

While theenciphering offthe message in the -manner described above maybe carried out by means of cutting the message in strips, assembly inpredetermined order, cutting at rightangles and reassembly in anotherpredetermined order 5 and the deciphering may be accomplished by mean-sof a mask which exposes the squares in a predetermined order, thesubject of the present application is a machine for carrying out theenciphering and deciphering automatically.

l0 The enciphering and deciphering machine of thepresent inventionconsists of a drum to which copy to be enciphered or deciphered isattached, a drum carrying photographic paper or film on which theenciphered or deciphered copy is re-` produced and means for projectingthe copy from the first drum on to the sensitized material on the seconddrum strip by strip in a predetermined order. f In particular, bothdrums are rotated at different speeds and a Strobotron lamp is flashedat predetermined instants whereby stripsv ond drum. The second copy,when developed, is

a positive copy of the original randomized in two dimensions. 4

An additional factor may be added by exposing only a portion of eachdrum, say one third, at ,I each run, repeating a second and third timeto completely cover the field in three runs. A simple mask may be usedto accomplish this additional randomizing. The mask is shifted and thekey changed, or a new starting point chosen as each portion of thecopyis randomized.

The completely enciphered copy may be-transferred by any suitable meansto a receiving point as, for instance, by wire or radio facsimile. Atthe receiving point the'message may be deciphered by repeating theenciphering process in rereciphered or remutilated by subjecting it tothe verse. The same machine above described is suitable for thisdeciphering.

In the drawing:

Fig. l shows a simple geometrical figure to be transmitted privately anda second figure included to add confusion.

Fig. '2 shows the figures of Fig. 1 partially enciphered.

including a large triangle representing the iigure which it is desiredto transmit to a receiving point and a small triangle added to confuse apossible interceptor.

Fig. 2 shows the result of dividing Fig. 1 into eight equal verticalstrips and rearranging these strips in a predetermined order. accordingto a key. Fig. 2 represents a partially enciphered copy. f

Fig. 3 shows the result of dividing the partially enciphered copy ofFig. 2 into eight equal horizontal strips and arranging these strips ina second predetermined order according to a second key. Fig. 3represents the fully enciphered copy.

'Ihe original copy may be restored by reversing the process, firstrestoring the original order of horizontal strips and second restoringthe order of the vertical strips. It will be noted in the encipheredcopy of Fig. 3 that the portions of the small triangle appear asconfusing elements of the same character as the portions of the largedesired triangle.

Fig. 4 shows a machine, according to the present invention, forenciphering or deciphering graphic COPY.

of predetermined width is projected upon second drum I8 by means ofsuitable optical system I1. Drum Il is rotated at a substantiallyconstant speed by means of motor I6, while drum I8 is advanced a step ata, time by a stepping device I9. For each position of drum I8 apredetermined section of copy 22 is projected onto drum I8 by means ofthe high speed flash lamp 5. A sheet of photographic paper or film isattached to the surface of drum I8 which when developed will reproducecopy 22 in randomized strips. Two strips are shown on drum I8 at 29 and2l.

When drum I8 has completed one revolution and the paper or filmdeveloped, a negative randomized strip image of copy 22 is produced.This represents the first step in enciphering the copy. To accomplishthe second step, the partially enciphered negative is attached to thesurface of drum I turned at right angles to the original position, sothat the strips run around the drum. The step by step randomized copyingprocess is carried out with a second photographic paper or nlm on drumI8 and using a second randomizing key. The result when this second paperor filmV is vdeveloped is a copy randomized in two dimensions that is insmall squares. This second enciphered copy will be a positive copy whichmay be transmitted to a receiving point by any well known means as, forinstance, by facsimile. Still further privacy may be provided byexposing only a portion of the length of the copy at each revolution ofdrum I8 and repeating the rotations until the entire drum is covered. Afurther degree of privacy may be added or substituted for this pastprocess by displacing the second copy by a fraction of a strip width ondrum I and repeating the two enciphering steps any desired number oftimes.

Lamp 5 may be ashed once at some predetermined point during eachrevolution of drum I and drum I8 stepped once at each revolution, orlamp 5 may be ashed two or more times at each revo- The subject drum Icarries on its surface'- graphic copy 22. A longitudinal strip of copy22 `2 of drum I.

4 lution of drum I,'stepping drum I8 once at each flash to produce aninter1aced" randomizing.

order oi' Momo@ second and may be triggered by means of an electricalimpulse. The timer unit 23 may be any well known device for flashinglamp 6 in accordance with electrical impulses fed to it over wires 24,21 and 29. Electrical impulses spaced corresponding to the desired stripwidth are generated by tone wheel 3 attached to shaft The number ofteeth on tone wheel 8 correspond to the number of strips to be producedfrom copy 22. Magnet 4 generates the tone wheel impulses which are fedto timer 23 over wire 24. Impulses from tone wheel 3, however, are notpassed to lamp 5 unless the circuits thru leads 21 and 29 are completed.The sequence of flashing of lamp 5 is controlled by the circuitsconnected to these leads 21 and 29.

On the same shaft with motor I6, driving drum I, are mounted acommutator I4 and collector rings 6, 1, 8. 9, etc. There are as manyycommutator segments in I4 as the number of strips into which the copyis to be photographically divided. `Assuming that the circumference ofdrum I would take subject copy 8" x 8 in size and that adequate privacywould be provided by using V2" strips, there would be 16 commutatorsegments and 16 collector rings, and 16 impulses per revolution would begenerated by tone wheel 3. The commutator I4 has a single stationarycontact I5,

and individual stationary contacts i3, I2, IIl I0,

connecting through contact I5 and the appropri,

ate collector ring contacts I3, I2, II, I0, etc. If connection is madeto I2, for example, the lamp circuit will be closed when the secondstrip is opposite the aperture lens I1; if connection is made throughIl), the Strobotron circuit will be closed when the fourth strip of theclear subject copy is opposite the lens I1, etc.

Functionally, the rotating switch 4I controls the lamp circuit and thestepping operation of the copying drum I8. This switch has a rotary armturned continuously by a back-geared motor not shown and sweepingcontinuously over the series of contacts shown. The third, sixth, ninth,twelfth, etc., contacts are marked 65, 69, 12, 15, etc. Immediatelyafter `each such contacts are contacts marked 66, 10, 13, 16, etc., andall of these contacts are connected together by means of connection 61.After each of these contacts fand before the next of the rst set ofcontacts are blank interval contacts marked 68, 1I, 14, 11, etc., whichare not electrically connected. After the final contact of the rst setof con- Lamps which provide illuminaadvantageous to gear the shaft ofthe switch 4I to the motor I6. l

'I'he operation of the rotary switch is such that as the arm 80 sweepsover the contacts, it rst closes a lamp selecting circuit from 65'(through a transportation block or set of blocks to be 'described) tosome one of the collector ring contacts I3, I2, etc.; this lattercontact corresponding to' the particularstrip of the subject copy ondrum I which is to be photographed in the first 'or top position on thesensitive paper carried by drum I8. After leaving 65, the arm 80 passesto'contact 66 which actuates the step-motor ISof drum I8, so as torotate drum I8 through an angle corresponding to one strip; thisoperation exposesl the second strip of the sensitive paper on drum I8through the lens I1. Rotary arm 86 next passes across idle contact 68 soallowing suiicient time for all mechanical transients to die down belfore the next photographing operation.' In some cases the idle periodsrepresented by contacts 66, 1I, etc., may be minimized or eliminated, ormerged into contacts 66, 10', etc. reaches contact 69 which is connectedto another one of the I3, I2, etc. collector contacts by way of thetransposition block or set of blocks, so setting up the lamp circuit tophotograph a different key-selected strip from the clear copy on drum Iin the second position on drum I8. This cycle is repeated until therotary .arm 80 has passed over all I6 of the 65, 69, etc. contacts andthe drum I8 has rotated through al1 I6 of its positions, with the resultthat the whole of the subject copy has been photographed upon thesensitive paper mounted on drum I8. The arm 80 then passes tostop-contact 64 which may automatically disconnect power from all parts,of thel machine andsignal that the operation has been completed byturning on a lamp or buzzer.

A simple form of transposition blocks for providing changes in the'keyis shown. They comprise cylinders 30, 42, 46 and 50, carrying numbersofcontacts 3|, 43, 41, 5I, etc., placed axially in rows of sixteen, andarranged to'be rotated either by hand orA automaticaly in steps bystepping motors 40, 45, 49 and 53, which may be simple magnetic pawlsand ratchets. On one side of the cylinders 30, etc.,'there are sixteenstationary contacts 3|, 43, 41, 5I`, etc., respectively connected to thecollector ring contacts I3, I2, II, IIJ, and on the other side aresixteen similar stationary contacts which are connected to contacts 65,69, 12, 15, etc., of the rotary switch 4I. Within the transpositionblock there are cross connec-" tions for each position between oppositesets of contacts, so that with transposition block 3l! in its firstposition, it will beconnected to a predetermined advanced contact onswitch 4I. The step control 40, etc., of the vtransposition blocks maybe connected to contact 64,so that. the transposition block will bemoved forward one step for each revolution of the rotary switch 4I.'I'his will result in selecting, in accordance .with the connectionswithin the various transposition blocks, the order in which the stripsof the subject copy on drum I will be photographed on drum I8. Forexample, if in the iirst position of drum I (exposing the top strip) andtherst position of the transposition block, collector ring contact I6 isconnected to rotary switch contact 65, the fourth Arm 80 next strip ondrum I will bephotographed into the :rst position on drum I8. In thesecond position of the transposition block, the twelfth strip on drum I'might be selected for photographing in the first position on drum I8,etc. Thus, the key'of the cipher is changed by rotating thetransposition blocks 30, 42, 46, from one step to another, or bysubstituting another diierently-connected transposition block. Evidentlythe invention is not limited to the number of transposition blocks usedas all four may be combined in one, two or any desired number ofcomposite blocks or they may be further divided.

In order to avoid irregularities in the timing of the lamp 5 such asmight result from contact diiculties if the commutator contact I5 alonewere `relied upon, it is proposed to use the commutator I4 only toestablish the desired circuit corresponding to the strip to bephotographed, and to rely upon a sharp impulse from a tone wheel 3-toignitethe lamp at exactly the instant when the desired strip to bephotographed on drum I is centered under lens I1.

The deciphering operation is mechanically and electrically the inverse`of that whichihas been described for` ciphering. 'I'he sametransposition blocks are used', but connected reversely, solas toreplace the randomized strips upon'rephotographing, into their originalpositions. The ciphered subject copy is placed on drum I and theresulting clear copy will come from drum I8 (after either two or fouroperations, according to the mutilation process used in ciphering).

The system of the present invention can be so applied as to give a longterm of privacy for graphic material,whether pictorial or textual. Theonly means of breaking the system would appear to be the tedious piecingtogether of the small square elements, Since these elements areidentical in size and shape, their contours offer no clues for theirreassembling. If they 'are made sufficiently small in relation to thecharacter of subject copy, the time required for their assembly shouldbe quite substantial.

The limitation of the system in term of privacy appears to be determinedprincipally by the mechanical and optical precision that canA be builtinto the ciphering and deciphering machine; it

is proposed. that by using the tone wheel and 'po-y sitioning stops ofrelatively large radius, a satisfactorilyhi'gh degree of mechanical'precision can be had Without too great diiiiculty.

The speed of operation of the system is not too strictly limited'. Ifhalf-inch strips, for example, gave adequate privacyfit is possible tomake the sixteen photographic exposures for each operation, in less thansixteen secondal and allowing two minutes each for developing, washingand blotting the photographs and replacing them on drum I, theenciphered message is produced in less than five minutes for a singlecross mutilation land in less than ten minutes for a double crossmutilation. This relatively short time required for enclphering ordecipheringv is made possible of strips and number ofphotographingoperations, the term of privacy can be extended by givmaybe shown as a series of dots'or dashes, thaty continental outlines orother identifying characingattention to the character of the originalclear subject copy.v For example, contour lines ters may be omitted andthe bench mark and overlay principle applied, and also that the clearmultiples of 90 degrees.

-for the copy to be transmitted, and filling the excess .area withsimilar graphic material having no significance. These and similarexpedients would incr-ease the difficulty of breaking the cipheredmessage byattempting to solve it as a picture puzzle, and thus increasethe term of privacy. (To date, no other way of breaking the cipher hasbeen discovered.)

A further element of complexity, based on the same principle ofautomatically randomizing the positions of equal-sized and identicallyshaped elements, may comprehend e, series of operations in which thesubject copy is processed three times at angles of 60. This would resultin the randomizing of a large number of equilateral triangles, ratherthan squares, but, while the process would generaly follow thesquare-element method outlined in the foregoing, the machine involvedwould be considerably more complicated. It is believed that adequateprivacy can be obtained by the square method without introducing thecomplications inherent in dividing the clear copy into triangular orhexagonal units,

Fig. shows a modified optical system which may be substituted for theoptical system I1 of Fig. 4 in order tr.- transfer graphic material fromdrum I to drum I8 a small square at a time instead of in strips. Thisoptical system oi' Fig. 5 includes suitable lenses 8i and 82 mounted inlens tube 89 for projecting a predetermined small square area 98 fromdrum I to a corresponding square area 99 on'drum I8. Drums I and I8 arerotated as in Fig. 4 and optical system 8 I-82-89 is moved along theaxial direction of drums I and I8 by suitable means as, for instance,motor 85 and gear 94 driving gears 92 and 93 attached to lead screws 90and- 9I. Lens assembly 8I-82-89 is mounted on lead screws 98 and 9| andis hence moved back and forth in accordance with the energizing of motor95, Motor 9 5' is energized over leads 96-91 from a contact or contactsas contact 63 on rotary switch 4I. Thus the motions of lens system8I-82--89 and drums I and I8 permit randomizing the copying of vmaterialfrom drum I on drum I8 a square at a time in a predetermined sequence. Acircumferential strip on the drums may be copied with the squaresrandomized within the strip, the lens system shifted the width of astrip, and the process repeated until the entire copy is transferred.

A further element of randomizing may be added by the use of means forrotating the squares being transferred by varying integral This may beaccomplished. for instance, by means of the totally refleeting 90-4545prism 83 which is included in the optical path between drums I and I8.This is a wel1 known optical device which rotates the image by an amountequal to twice the physical rotation of the prism. Thus the orientationof the material within a square may be randomized, Prism 83 may berotated by any suitable means as, for instance, motor 88, gear 85attached to the shaft of motor 86 and ring gear 84 attached to lens tube89 carrying prism 83. The exact positioning of prism 83 at angularpositions which are integral multiples of 45 degrees may be insured bydetent operating on a notch in the side of ring gear 84 and at arelatively long radius for high accuracy. Motor 88 may be energized alsofrom apoint on rotary switch 4I thru leads 81-88. Hence, with themachine ofFig. 4 as modiiied in Fig. 5, is capable of dividing copy intoa large number of squares in which the image within the individualsquares is rotated by 0, 90. or 270 degrees and in which the location ofthe squares is randomized within any circumferential strip. Completerandomization oi the p0- sitions of the squares may be accomplished bymoving. either drum I or drum I8 along its axis by predetermined amountsduring the copying process.

Any degree of privacy may be attained by repeating the randomizingprocess with the copi' randomized in a previous operation displacedalongdrum I by a predetermined fraction oi a square width. For instance,the randomizlng may be carried out three times with the partiallyenciphered copy displaced one-third and two-thirds of a square width forthe second and third passes respectively.

Further privacy may be attained using any given degree of randomizing byspecial treatment of the copy to be enciphered. One very effectivemethod of preparation is to use dotted lines on the original copy, sothat no continuous lines appear at the edges of the squares to assist inmatching. Preparation of the copy so that only one dot appears in eachsquare and especially if this one dot is made to appear at the center ofths square provides enciphered copy which is impossible of breaking"within moderate period of privacy.

The machines described above have been explained as applied to theenciphering process. The enciphered copy is transmitted to a receivingpoint by facsimile, messenger or other suitable means. The received copymay be deciphered on the same machine used for enclphering, by invertingthe order of randomizing. y

While one embodiment of the present invention with a few modificationshas been shown and described, many modifications are possible within thespirit and scope of the invention, as set forth in the appended claims.

What is claimed is:

1. In an enciphering device for graphic materia1 privacy, thecombination of, means for reproducing the original graphic'material instrips mixed in a predetermined manner, and means for determining theorder of mixing to form an enciphered copy.

2. In an enciphering device for graphic material privacy, thecombination of, means for reproducing the original graphic material insquares mixed ina predetermined manner, and means forv determining theorder `of mixing t0 form an enciphered copy.

3. In an enciphering device for graphic material privacy, thecombination of, nieans for reproducing substantially square areaportions of said graphic material, means for rotating predeterminedsquares by predetermined amounts, and means for mixing the rotated andunrotated squares in predetermined order to form an enciphered copy.

4. In an enciphering device for graphic material privacy, thecombination of', a drum for carrying copy to be enciphered, a drum forreceiving enciphered copy, an optical system and light source forphotographically transferring the copy from the first said drum to thesecond said drum a. portion at a time, means for rotating said drums,and means for energizing said light source when said drums are invarious predetermined relativepositions for forming an enciphered copi1on the second said drum.

5. In an enciphering device for graphic material privacy,V thecombination of. a drum for carrying copy to be enciphered, a drum forreceiving enciphered copy, an optical system and llight source forphotographically transferring the copy from the first said drum to thesecond said drum a portion at a time, means for rotating said drums, andan interchangeable key-block for energizing said light source when saiddrums are in various predetermined relative positions for forming anenciphered copy on the second said drum.

6. In an encipherlng device for privacy of graphic material, thecombination of, means for holding original copy to be enciphered, meansfor holding a photo-sensitive sheet to receive an enciphered copy, anoptical system for projecting a. small square area from the originalcopy to the Vphoto-sensitive sheet, a high speed flash Ylamp forilluminating said small area of copy,

means for moving the original copy, photo-sensitive sheet, and opticalsystem thru a plurality. of relative positions to scan the originalcopy, and means for flashing said lamp at predetermined relativepositions to form an enciphered copy of said original on saidphoto-sensitive sheet. 7. In an enciphering device for privacypreparation of graphic material, the combination oi', means for holdingoriginal copy to be enciphered, means for holding a photo-sensitivesheet to receive an enciphered copy. an optical system in- REFERENCESCITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,855,370 Trenor Apr. 26, 1932 D.29,195 Standing Aug. 9, 1898 156,851 Joseph Nov. 17, 1874 280,878Stranders July 10, 1883 '2,078,646 Treinis Apr. 27, 1937 1,379,905 DownMay 31, 1921 2,089,632 Watson Aug. 10, 1937 1,383,097 Gibson June 28,1921 FOREIGN PATENTS Number Country Date 7 ,280 Great Britain e 1913OTHER REFERENCES Websters 1939 Unabridged Dictionary under Random pages2059 and 2060.

